Unwanted particles and contaminants can accumulate on the surfaces of workpieces (or objects), such as semiconductor wafers and component parts, in a variety of industries. Undesirable particles are generally introduced to the objects by the external environment. However, frequently, the undesirable particles are introduced as a result of the fabrication of the objects during manufacture. In the field of data storage systems, fabricated disc drive components have become increasingly sensitive to particles and contaminants deposited on the surfaces of component parts. To increase recording density in data storage systems, it has become desirable to reduce the fly height over the data storage media. After assembly of a data storage system and during data storage system operation, serious damage to the data storage media and a loss of data can result if particles become present at the head and data storage media interface. Particles that are present at this interface can cause performance problems such as media defects, thermal asperities, stiction, head crash or catastrophic drive failure.
Acoustic energy, in the ultrasonic and megasonic frequency ranges, is commonly used to clean undesirable material off of component parts. Typically, a cleaning system includes a cleaning bath that holds a wash fluid in which component parts are immersed for cleaning. The wash fluid can contain various chemical solutions as well as various temperatures and dissolved gas concentrations. The cleaning bath has an array of ultrasonic transducers that are coupled to the bottom and/or sides of the bath. The transducers emit an ultrasonic or megasonic frequency which permeates the bath and the bath's wash fluid and cleans the component parts.
The maximum cleaning efficiency of the cleaning bath, however, can be compromised in a single wash fluid cleaning system. Cleaning variables such as time, temperature, power, chemistry, dissolved gas concentration, cleaning bath design and acoustical energy compete for maximum cleaning efficiency. For example, it is known that a lower dissolved gas concentration in a cleaning system increases particle removal, but it has also been demonstrated that some level of dissolved gas is needed to remove particles. In addition, control and use of the above-identified variables increases the amount of energy, time, chemicals, system size and costs needed to power the cleaning system.